California researchers find autism-pesticide link

CHILDREN OF WOMEN IN CENTRAL VALLEY WERE FOCUS OF STUDY

Pregnant women from the Central Valley who were exposed to high levels of pesticides were up to six times more likely to give birthto a child with autism or a related disorder, state health officials said Monday.

California Department of Public Health researchers studied 465 children with autism spectrum disorders in 19 counties born between 1996 and 1998, comparing them with a control group of nearly 7,000 other children.

They found that women who lived close to fields with the highest use of a group of pesticides known as organochlorines were the most likely to bear children with the disorders, which range from mild to severe and cover a wide array of neurological and developmental problems, including difficulties with speaking, social interaction and motor skills.

Of 19 pesticides studied, only the organochlorines had a significant association with autism disorders. Organochlorines include endosulfan and dicofol, two pesticides whose use, primarily on cotton crops, has declined "dramatically" in the past few years in favor of newer, less toxic, pesticides, said Glenn Brank, a spokesman for the California Department of Pesticide Regulation.

Although scientists have previously linked certain other pesticides to neurological problems and developmental delays in children, this is the first study to examine possible connections between pesticides and autism disorders, said Dr. Mark Horton, director of the Department of Public Health.

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Horton emphasized that the study does not prove pesticides actually caused the autism disorders, but that there is a possible link that merits further study. The study also suffers from a small sample size: The researchers identified 29 women at the highest-risk of exposure and found that eight of them gave birth to children with autism or a related disorder.

Still, the study's conclusions, while tentative, are important, Brank said, noting that the pesticide regulation agency already is studying whether to further restrict already tightly controlled endosulfan. A similar review of dicofol is planned. The agency will be working closely with public health officials to share information, he said.

"The implications of this study we are taking very seriously," Brank said.

Isaac Pessah, a researcher with the University of California-Davis' MIND Institute, which studies autism, described the study as well-conducted, if small. Scientists need to look at larger populations to better define the relationship between pesticides and autism, he said. This line of research also could divert attention from studying the purported role that mercury and vaccines have in causing autism, a link that largely has been debunked, he said.

The California Department of Public Health study was posted online Monday by the journal Environmental Health Perspectives and will be published in an upcoming issue.

IF YOU'RE INTERESTED

The Environmental Health Perspectives article is available at www.ehponline.org.